JP2001278715A - Silver-supporting antimicrobial agent for water treatment and its application method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that fine-grain silver zeolite needs to be used as compacts in a consolidated condition and the elution concentration of silver cannot be regulated because the particle size of silver zeolite used this present is in a micron order and solid-liquid separation in water is impossible for the present particle size of silver zeolite when used for water treatment and therefore silver zeolite cannot directly be thrown into an aqueous solution. SOLUTION: A silver-supporting antimicrobial agent for water treatment is prepared by making zeolite particles or zeolite-based processed products, which enables solid-liquid separation for water treatment and has an optional size, directly support silver in a treating liquid showing such a pH value as does not destroy the crystal structure of zeolite. The silver-supporting antimicrobial agent for water treatment is used as a silver-supporting material alone where a material composed of the zeolite particles or zeolite-based processed products mentioned above is made to directly support silver or as a combination of the silver-supporting material with a material not supporting silver in such a way as to enable the elution concentration of silver to be regulated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an antibacterial silver-carrying agent for water treatment and a method for using the same. The present invention relates to a silver-carrying antibacterial agent for water treatment and a method of using the same, which significantly simplifies the production process by having the silver zeolite supported and has higher performance than conventional products using fine-particle silver zeolite.

[0002]

2. Description of the Related Art As the demand for water increases, the quality of water is required to be improved, and a more harmless and appropriate water treatment method is desired. Above all, it has been required and developed that silver zeolite can be used as an antibacterial agent for water treatment by taking advantage of its excellent antibacterial properties. Currently used silver zeolite particles are on the order of microns. However, for water treatment, silver zeolite cannot be directly introduced into an aqueous solution because solid-liquid separation cannot be performed in water depending on the current silver zeolite particle size. Therefore, it is necessary to solidify such fine particles of silver zeolite and use it as a compact. However, since zeolite itself has no self-bonding property, it is molded by adding a binder. The antibacterial performance per unit weight is lower than that of the original silver zeolite powder by the amount of the binder, but at present, this method is adopted because the advantage of using it as a molded article is greater. Some of the things the industry is currently developing include: (1) A type zeolite having a particle size of 1 to 2 μm is contacted with an aqueous silver nitrate solution to obtain a silver zeolite having a silver content of 2 to 2.5%, and the silver zeolite is added to a synthetic resin at 1 to 10% and molded. Particle size is 0.5 to 2.0 mm to 5 to 1
0 mm. The purpose of this development is to store tap water from which chlorine has been removed under aseptic conditions in a water tank. It is said that good results were obtained when 10% of silver zeolite was added and the molded resin was added in an amount of 10% of water. (JP-A-4-
294782). (2) In the same manner as in (1), a silver zeolite having a silver loading of 2 to 2.5% was prepared using A-type zeolite as a carrier, and an equal amount of a binder CaCO ₃ was mixed with the zeolite.
Add 0% bentonite, wet mix and extrude into pellets. After drying, the pellets are fired at 550 ° C. for 3 hours. The size of the product is 1/16 inch and the silver content is 0.89% (JP-B-63-28402). (3) The synthetic resin particles having a size of 3 to 5 mm are rotated at a high speed by a mixer, and when melting starts, toluene is charged into the mixer, and fine powder of silver zeolite is sprinkled on the mixture, and silver is directly applied to the surface of the synthetic resin particles. One coated with zeolite. The purpose of this development is that it is not preferable to put silver zeolite directly into water as it is, and in the case of an antibacterial agent for water treatment formed by mixing silver zeolite with synthetic resin, the antibacterial function is limited only to the surface. (Japanese Patent Application Laid-Open No. 5-176976).

[0003]

As described above, in the present circumstances, in order to obtain particles of a certain size, fine particles of silver zeolite are used to obtain particles of a certain size. Method of molding b) A method of mixing with a synthetic resin and molding with an injection molding machine is used. The present inventor is currently conducting a),
(2) Avoid the process of first preparing silver zeolite, adding it to a binder, or mixing it with a synthetic resin and molding it, and crushing zeolite molded products with large particles or natural zeolite. We succeeded in carrying silver easily on the sample. In the method developed this time, silver is directly supported on a zeolite particle or zeolite-based processed product of an arbitrary size, which is a raw material, in a processing solution having a pH that does not destroy the zeolite crystal structure. Not only particles having a diameter of 2 to 3 mm, but also larger zeolite particles and zeolite-based processed products can be loaded with silver, and the production process is greatly simplified, and at the same time, the products of the above a) and b) An antibacterial agent for water treatment with much better performance could be made. Therefore, silver for water treatment, in which silver is directly supported on a zeolite particle or zeolite-based processed product of any size capable of solid-liquid separation for water treatment, in a treatment liquid having a pH that does not destroy the crystal structure of zeolite, It is a first object of the present invention to provide a supported antibacterial agent. A method for using a silver-supported antibacterial agent for water treatment that enables the adjustment of silver elution concentration by using only a silver-supporting material in which silver is directly supported on such a material or by combining a silver-supporting material and a silver-free material. Providing the second aspect of the present invention.
Subject. As a carrier for supporting silver, a natural zeolite ore, a natural zeolite processed into spherical, cylindrical, columnar, cylindrical, etc., an A-type zeolite-based molded product, A
A fired product made from a zeolite as a raw material, the shape of which is spherical, columnar, cylindrical, coin-shaped flake, sheet, etc., and an artificial zeolite-based molded product described in 1995 Patent No. 2555731, and a fired product thereof Etc.

[0004]

SUMMARY OF THE INVENTION The present invention provides a treatment liquid having a pH that does not destroy the zeolite crystal structure in zeolite particles or zeolite-based products of any size that can be separated into solids and liquids for water treatment. It is a silver-supported antibacterial agent for water treatment in which silver is directly supported in water. According to the present invention, silver is directly supported on a zeolite particle or zeolite-based processed product of any size capable of solid-liquid separation for water treatment in a processing solution having a pH that does not destroy the crystal structure of zeolite. This is a method of using a silver-carrying antibacterial agent for water treatment, which makes it possible to adjust the elution concentration of silver using only a silver-carrying material or a combination of a silver-carrying material and a silver-free material.

[0005]

The method of supporting silver on the synthetic zeolite of fine particles is stopped, and as shown in the Examples, silver is directly applied to zeolite particles having a size that can be used as an antibacterial agent for water treatment or molded zeolite particles. Was attempted to be carried. A natural zeolite crushed product as a carrier carrying silver, A
Zeolite rod-shaped molded product (diameter 1.5 mm), A-type zeolite coin-shaped molded product (diameter 25 mm, thickness 2-3 m)
m) and other mullite molded articles having a certain size. Good results were obtained for all of these samples. That is, It became. As for the A-type zeolite-based molded rod, the column elution test, the adjustment test of the silver elution concentration, and the long-term elution test using a beaker were performed with tap water using SV5 and SV20. It was confirmed.
Natural zeolites are abundant in Japan and inexpensive. However, the amount of silver supported is limited to 5 mg-Ag / g-Z, and has not been successful as an antibacterial agent. However, when the raw rock of the mordenite natural zeolite produced in Fukushima Prefecture was crushed and silver was supported by the method of the present invention, 145 mg of Ag was supported per g of zeolite. Furthermore, a column elution test was performed using these silver zeolites, and as a result of preparing three groups of columns and testing the elution of silver and the adjustment of the silver elution concentration, natural zeolite carrying silver was synthesized as an antibacterial agent for water treatment. It is considered that there is a standard that can be used together with the A-type zeolite-based molded product. Further, since the manufacturing process is significantly simplified, the production cost can be reduced. A-type zeolite has a high concentration of aluminum contained in the crystal lattice, a high ion exchange capacity, and a high silver-carrying capacity, but has a low acid resistance, and its crystal structure collapses when immersed in a solution having a pH of 5 or less. Therefore, an important feature of the method for producing the silver-supported zeolite as the antibacterial agent for water treatment of the present invention is that the concentration of the silver-supporting treatment solution is kept at pH 5 or less and the amount of the aqueous solution per 1 g of zeolite is reduced. That is, the amount was extremely increased. Hereinafter, a comparison with the conventional product is shown. As described above, as a result of extremely increasing the amount of the aqueous solution per 1 g of zeolite, the concentration of the processing solution for supporting silver was not reduced to PH5 or less, and the amount of silver supported per 1 g of zeolite and per 1 g of zeolite were reduced. The weight percent of supported silver was as described above. When the silver-supported antibacterial agent for water treatment of the present invention is used in tap water, the tap water contains chlorine, but there is no problem in its efficacy because the silver-supported antibacterial agent has a large amount of silver carried. .

[0006]

Example 1 A description will be given of a silver adsorption test of a natural zeolite raw rock. The raw rock of mordenite natural zeolite from Fukushima Prefecture is crushed and the particle size is 1.68 to 2.00 m using a sieve.
m and a silver adsorption isotherm was created. After pretreatment such as washing, drying and degassing, the sample is transferred to a 200 ml beaker,
After adding silver nitrate at a predetermined concentration and shaking at room temperature for 1 hour, the mixture was filtered through a membrane filter having a pore size of 0.45 μm, and the silver concentration in the filtrate was quantified by graphite furnace atomic absorption spectrometry. Thereby, the adsorption isotherm of silver of FIG. 1 was created. As shown in FIG. 1, the silver concentration is 150 to 2500 m.
In the range of g / L, the adsorption of silver is 8.0 to 90 mg-Ag / g.
-Z. Thus, the characteristics of supporting silver on natural zeolite could be confirmed.

[0007]

Example 2 Next, a description will be given of a test for elution of silver from a natural zeolite carrying silver. Considering the antibacterial properties of silver, for example, in the case of Escherichia coli, there is a clear effect at 5.0 μg / L or more, and regarding the safety, considering that the US tap water standard is 50 μg / L or less. In practice, it is necessary to adjust the silver elution concentration. Therefore, according to the adsorption isotherm preparation method, the supported amount of silver was 56 and 14
A silver-supported natural zeolite for column elution test of 5 mg-Ag / g-Zeolite was prepared, and three types of columns as shown in FIG. 2 were prepared using these silver-supported zeolite and silver-free zeolite to prepare silver. A dissolution test was performed. At this time, a glass column having an inner diameter of 15.5 mm was used, silver-loaded natural zeolite was put into the column, ion-exchanged water was allowed to flow down from above with SV5, and the silver concentration in the effluent was quantified by graphite furnace atomic absorption spectrometry. The result is shown in FIG. Silver 5
In column 1 having a 6 mg-supported zeolite layer height of only 20 cm, the elution concentration of silver is in the range of 2.5 to 5.5 mg / L, but the unsupported zeolite layer is located below the 145 mg silver-supported zeolite layer height of 2 cm above the column. In column 2 packed at a height of 18 cm, the elution concentration is 0.05 to 0.3 mg / L.
Further, in column 3 in which an unsupported zeolite layer height of 36 cm was packed under a 145 mg silver-supported zeolite layer height of 2 cm at the top of the column, the elution concentration was 0.01 to 0.0
It became 6 mg / L. Thus, it was found that when the non-supported natural zeolite was placed under the silver-supported natural zeolite, the elution concentration of silver could be adjusted, and it was confirmed that it could be used as an antibacterial agent.

[0008]

Example 3 Synthetic A-type zeolite molded product (rod-shaped diameter 1.
5 mm) of silver will be described. Synthetic A type zeolite molded product is A4 type zeolite 60% and Kibushi clay 30
% And bentonite 10%, and paste (CMC2
% Solution), kneaded, extruded into a rod having a diameter of 1.5 mm, air-dried, and then fired at 600 ° C. for 3 hours. After treating this type A zeolite molded article with silver nitrate at a predetermined concentration, the silver concentration becomes 100%.
Silver adsorption is 19.76-4 in the range of -5000 mg / L.
It became 80 mg-Ag / g-Z. As shown in FIG. 3, the silver adsorption characteristic on the A-type zeolite molded article could be confirmed from the adsorption isotherm of silver. Further, according to the method of preparing the adsorption isotherm, the amount of silver carried was 533.0 mg.
-Ag / g-Z sample was obtained.

[0009]

EXAMPLE 4 Next, a description will be given of a test for elution of silver from the synthetic A-type zeolite molded product of Example 3. Inner diameter 15.5
sample supporting silver on a 50 mm glass column (533.0).
mg-Ag / g-Z) in an upper layer of 2.5 cm, and a silver-free zeolite (A-type zeolite) in a lower layer of 36 cm.
The column was packed and assembled, and tap water was allowed to flow down from above with SV5. Silver concentration in tap water flowing down from the column was determined by graphite furnace atomic absorption spectrometry. Tap water that passed through the column was not circulated. Elution time was 126 hours, passed tap water was 17.29 liters, and samples were collected almost every two hours. During the first 28 hours, the eluted silver concentration ranged from 300 to 450 ppb. From 30 hours to the end, the concentration of eluted silver is almost 200 p.
It showed equilibrium in pb. Although the silver in the silver-carrying sample had an extremely high concentration, it was confirmed that the concentration of the eluted silver could be adjusted by such a two-layered column. Incidentally, the analysis results of tap water by ion chromatography are as follows. Tap water is PH 7.86 (15.7 ° C) μs / cm 225

[0010]

Example 5 This example is a dissolution test under more severe conditions than the dissolution test of silver of Example 4, and was performed on the premise of an actual operation. The configuration of the column was not a combination of silver-carrying and silver-non-carrying, only silver-carrying zeolite,
The sample was 418 mg-Ag / g-Zeolite and the layer height was 6 cm (11.3 cm ³ ). The SV was set to 20 (3.8 ml / min). Use tap water for a total of 12
Tested for 7 hours. The amount of tap water passed was 17596 ml. The concentration of eluted silver was 20 times to 29 ppm out of 18 times, 7 times 19 ppm or less, 6 times 30 to 36 ppm, and 5 times. The amount of silver eluted was 415.5 m calculated from the silver concentration (mg / L) and the amount of passing water L in each measurement section.
g, the silver content of the silver-carrying sample was 4180 mg (418 mg
-Ag / g-Zeolite × 10 g), which indicated that about 10% of the amount of silver contained in the silver-supported sample was eluted.

[0011]

Example 6 A long-term dissolution test of a silver-supported A-type zeolite molded product in tap water was performed. 1) Using a silver-supported A-type zeolite molded product (silver supported amount)
418mg-Ag / g-Zeolite) 2) Usage amount 1g 3) Tap water 1000ml Replaced with fresh tap water after a certain period of time 4) Stir with magnetic stirrer 5) Total stirring time 1848 hours From the above, tap water 100 for 1848 hours
The mixture was replaced by 0 ml at a time and stirring was continued. Initially, at the first and second starts, a large amount of silver was peeled off from the surface layer of the silver-supported particles, resulting in high-concentration elution. It was confirmed that the elution showed a stable concentration until 1848 hours when the stirring was stopped. In addition, even when the dissolution test was completed, the dissolution of silver did not deteriorate, confirming that the silver-carrying antibacterial agent could be used in tap water for a long time with a small amount.

[0012]

EXAMPLE 7 A coin-shaped flake (diameter 25 mm, thickness 2-3 mm) was fired using A-type zeolite as a starting material. A silver loading test was carried out for each of the firing temperatures. If the firing temperature is low, the strength of the product is weakened, and if the firing temperature is high, the framework structure of zeolite is broken. As a result of this test, the firing temperature is preferably from 600 to 640 ° C.
When the amount of Ag per liter is around 2500mg,
It has been found that favorable results are obtained. From the table above, the amount of silver carried per gram of the molded product was from 128.23 mg to 418.
It is in the range of 58 mg, with a maximum silver loading weight percent per gram of zeolite of 41.86% (sample no. 5).

[0013]

According to the present invention, there is provided a method for water treatment, which does not use a conventional method of producing silver zeolite, adding it to a binder, or mixing it with a synthetic resin and molding it. Since silver is directly and easily supported on a zeolite molded article having a large particle size or a crushed natural zeolite, the production process is significantly simplified, and as a result, the production cost is reduced, and There is an effect that an antibacterial agent for water treatment having much higher performance than conventional products can be produced. In the present invention, silver can be directly supported not only on a zeolite or a zeolite-based processed product but also on a refractory viscosity mullite or a mullite-based processed product. According to the present invention, the amount of the aqueous solution with respect to the zeolite is extremely increased as compared with the conventional one. As a result, the concentration of the processing solution for supporting silver does not drop to PH5 or less, so that the crystal structure of the zeolite does not collapse, and at the same time, the zeolite does not collapse. This has the effect of realizing a high amount of silver supported on silver. Also,
According to the present invention, it is possible to use only a silver-carrying material having silver supported on a carrier, but it is possible to adjust the silver elution concentration by a free combination of a silver-carrying material and a silver-free material not carrying silver. Has the effect. The silver-supported antibacterial agent for water treatment according to the present invention has a bactericidal and fungicidal effect when used in drinking water, pools, water purification plants, cooling towers, water-soluble oils, bath water, shaking humidifiers, etc., especially Legionella. It can be used for a wide range of water treatments such as prevention of diseases, suppression of algae in cooling towers, removal of slime, prevention of clogging in mechanical cooling circuits, prevention of decay of water-soluble oils, and countermeasures against odors.

[Brief description of the drawings]

Fig. 1 Crushed granules of natural zeolite raw rock (1.68 ~
2.00 mm) is a graph showing an adsorption isotherm of silver.

FIG. 2 is a column 1 of only supported zeolite in which crushed natural zeolite particles of FIG. 1 support silver, and columns 2 and 3 in which silver-supported zeolite and silver-free zeolite are combined.
3 is a graph showing the elution state of silver when three types of columns were prepared and a silver elution test was performed. ○ In the case of a zeolite layer carrying 56 mg of silver and 20 cm in height (column 1) △ In the case of a zeolite layer carrying no zeolite and a height of 18 cm below a height of 2 cm of the zeolite carrying 145 mg of silver (column 2) □ A zeolite layer carrying 145 mg of silver When the unsupported zeolite layer height is 36 cm below the height of 2 cm (column 3)

FIG. 3 is a graph showing an adsorption isotherm of silver of a molded product of type A zeolite.

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C02F 1/50 540 C02F 1/50 540E 540F

Claims (2)

[Claims] 1. Zeolite particles or zeolite-based processed products of an arbitrary size capable of solid-liquid separation for water treatment are directly supported with silver in a treatment liquid having a pH that does not destroy the crystal structure of zeolite. Silver carrying antibacterial agent for water treatment. 2. Zeolite particles or zeolite-based processed products of any size capable of solid-liquid separation for water treatment are directly supported with silver in a treatment solution having a pH that does not destroy the crystal structure of zeolite. A method of using a silver-carrying antibacterial agent for water treatment, which makes it possible to adjust the elution concentration of silver using only a silver-carrying material or a combination of a silver-carrying material and a silver-free material.